Problem: Express this product in scientific notation: $(3.90\times 10^{6})\times (9.00\times 10^{1})$
Answer: Start by collecting like terms together. $= (3.90\times 9.00) \times (10^{6}\times 10^{1})$ When multiplying exponents with the same base, add the powers together. $= 35.1 \times 10^{6\,+\,1}$ $= 35.1 \times 10^{7}$ To write the answer correctly in scientific notation, the first number needs to be between $1$ and $10$ . In this case, we need to move the decimal one position to the left without changing the value of our answer. $ $ We can use the fact that $35.1$ is the same as $3.510 \times 10$ $ = {3.510 \times 10} \times 10^{7} $ $= 3.510\times 10^{8}$